Recently, a recording and reproducing apparatus having a cartridge holder into which a disk cartridge made of a rigid material is inserted has been developed. The disk cartridge receives a magnetic disk rotatably therein. The apparatus includes cam members having angular holes, flat portions and inclined portions for pushing up the holder. The cartridge holder is operatively connected with and, disconnected from, the apparatus by the action of the cam members and rollers which are disposed on the sides of the holder. However, if errors occur in the positions or dimensions of the angular holes, the inclined portions and the rollers, the cartridge holder is not smoothly connected to the apparatus operatively.